Banding/Grainy Problems - Roland SP540V

Newbie to the forum who needs some help. I have a Roland SP540V printer with horizontal banding and grainy/noisy prints. We've had several different "Repair" techs out and haven't been able to solve our problem, just make excuses like "there's some bad ink in there, you just need to run it til its prints itself out". They've replaced our dampers, replaced a head (dark), and have cleaned everything.

I am using 3M 3M180IJ white vinyl as my media. When you run a test print all the lines on the test print look perfect, so I am sure the print heads are not the problem. The tech said it was probably a bad black ink cartridge, but he drained the black ink out of the lines and put a fresh black ink cartridge in and the problem still exists. I tried switching from bi-directional to unidirectional, but you can see from the pictures below that the problem exists on both prints. After reading some forum threads, we think it could be our profile settings...anything pop out as problematic?

With Max Impact off, its even worse...more grainy and gets lighter in the banding. When the repair guy was here, it started out with a lot of missing lines. He changed the dampers, saw some improvement, then he replaced the Dark Head and it was showing perfect nozzle checks. Even though the nozzle check was perfect when he was here, we still saw the graininess & banding. Now we have a dark line going down the middle (see pic)

Not sure why you have a line like that in between your repeated test print- that could be causing your bands. Did you have a head strike after the head was changed? Did he print the head alignment after replacing the head and leave it with you?

Look at your nozzle test. Do you see the overlap lines in the middle? There should be the same distance between those lines as the rest. You have a calibration and or an alignment issue. Did the tech go thru the complete head replacement alignment and calibration while repairing the machine?
I believe therein lies you problem.

That makes total sense. When we print out long runs of decals, anything past 3-4ft, the cutline starts getting exponentially off center. Up until now, we just thought it was a cutting issue, but now that you point out the print is not straight after the messed up line, its obvious the printing is what is being skewed off center and the cutting process is probably correct.

Thank you all for sharing you knowledge! The repair guy is coming back over this afternoon, now we are armed with at least some understanding of whats the issue. I'll let you know what happens.